Crayfish Microhabitats Provide a Close Association with Benthic Microbiomes to Support Cleaning Symbionts.

Stream ecosystems promote variable microhabitats along a longitudinal gradient. These microhabitats support dynamic biotic assemblages. One such microhabitat in freshwater streams involves the external surface of crayfish. We investigated the microbiome of crayfish exoskeletons and the surrounding environment (water and substrate) in association with the presence and abundance of crayfish cleaning ectosymbionts (branchiobdellidans). These ectosymbionts actively consume the biofilm on crayfish as they live and reproduce in association with crayfish microhabitats. Sequenced microbes of the environment and crayfish were compared for dominant taxa. While the sample types (water, substrate, and crayfish) had significantly different microbiomes, there was not a significant difference in the microbiome of crayfish with and without branchiobdellidans. The findings indicated that the stream substrate with its associated lotic interactions influences and supports the microbial and symbiotic organisms found living on the surface of the crayfish.